Rotors for use during the processing of liquids are known. One such rotor, described in U.S. Pat. No. 3,901,658, discloses a rotor assembly for performing photometric analyses using whole blood samples. The rotor assembly includes a cell sedimentation bowl for centrifugally separating red blood cells from plasma. Following separation, the plasma is displaced from the sedimentation bowl, and measured sub-volumes are distributed to respective sample analyses cuvettes positioned in an angular array about the rotor periphery. Another rotor, described in U.S. Pat. No. 4,515,889 is utilized for mixing and incubating a sample solution with at least one reagent and optically measuring a parameter in the incubated reaction mixture. Each step of mixing, incubating and measuring is carried out under the influence of centrifugal forces generated by the rotation of the rotor. Other examples of rotors are set forth in the referenced co-pending patent application Ser. No. 074,739, filed Jul. 17, 1987, U.S. Pat. No. 4,835,106, issued on May 30, 1989, whose disclosure is incorporated herein by reference.
Historically, the aliquoting of liquid samples and diluents for use in a rotor has been performed by hand prior to introduction of the aliquot within the rotor for a processing step. It would be desirable to provide a rotor wherein a measured amount of aliquot can be automatically separated from an excess amount of liquid introduced within the rotor without the use of capillary tubes, moving parts supported within the rotor or manual intervention of an analyst.
In addition, transfer of liquids within the rotor from one chamber of the rotor to another for processing purposes has presented difficulties due to space limitations within the rotor which can be dedicated to transfer mechanisms. Hence, it would also be desirable to provide a rotor wherein liquid can be transferred from one character of the rotor to another without the use of transfer mechanisms internal of the rotor. Moreover, it would be desirable to provide a rotor having an internal passageway opening through which liquid is prevented from passing prior to the occurrence of a predetermined event, such as the insertion of a capillary tube through the passageway opening.
Conventional rotors are commonly limited in that only a limited number of processing steps can be performed within any one rotor. When analyzing a whole blood sample, for example, a large number of processing steps may be involved including a separating of plasma component of the sample from the cellular component, obtaining a measured aliquot of plasma and then mixing the aliquot with a reagent to induce a reaction which is monitored. Additional processing steps may include dilution, separation, protein removal and washing.
Other examples of an analysis method or technique involving a large number of processing steps are enzyme-linked immunosorbent assay (ELISA) and heterogeneous enzyme immunoassays which are used to detect and quantitate either antigens or antibodies in biological samples. The ELISA technique utilizes enzyme-labeled immunoreactants (antigen or antibody) covalently bound to a solid support such as the inside of test tubes, the surface of beads, or the surface of individual wells in microtiter plates. Although popular and widely used in bioanalysis, ELISA assays are difficult to completely automate since they require separation of free-labeled antigen (or antibody) from the labeled antigen (or antibody) bound to the solid support. Also, ELISA procedures require a series of sequential manipulations in order to perform an assay. For example, even a simple ELISA procedure requires sample preprocessing and metering, multiple reagent additions, incubations and washings, reaction monitoring, and data acquisition and processing.
Traditionally, an ELISA procedure is performed in a single reaction chamber which contains the immobilized antibody or antigen. Aliquots of sample, reagents, wash solutions and like substances are introduced into or removed from the single reaction chamber in accordance with the processing step desired to be conducted within the chamber. It is common, however, that several steps in the procedure are performed external to the reaction chamber in preparation of various ones of the processing steps to be conducted within the chamber. Such externally-performed tests render the analysis process time-consuming and subject to errors for which an analyst may be responsible. Furthermore, during tests such as may involve an enzyme-linked immunosorbent assay (ELISA) used to detect the presence of an AIDS antibody, the analyst could be exposed to a biohazardous sample during the performance of external processing steps. It would be desirable to provide a rotor within which a relatively large number of processing steps can be automatically performed thus limiting the number of external processing steps necessary during analysis and increasing the safety of an analysis during some types of testing. In particular, it would desirable to provide a rotor system which automates all of the steps of the ELISA procedure.
Accordingly, it is an object of the present invention to provide a new and improved rotor for use during the processing of liquids.
Another object of the present invention is to provide such a rotor and method for use wherein a measured aliquot of liquid is automatically separated from an excess amount of liquid without the use of capillary tubes, moving parts supported within the rotor or manual intervention of an analyst.
Still another object of the present invention is to provide such a rotor having at least two internal chambers wherein liquid is transferred from one chamber to another without the use of transfer mechanisms internal of the rotor.
Yet another object of the present invention is to provide such a rotor having an internal passageway opening through which liquid is not permitted to pass prior to the occurrence of a predetermined event, such as the insertion of a capillary tube through the passageway opening.
A further object of the present invention is to provide such a rotor within which a relatively large number of processing steps can be automatically performed.
A still further object of the present invention is to provide such a rotor which is particularly well-suited for analyzing whole blood samples and which increases the safety of an analyst during the processing steps.
A yet further object of the present invention is to provide such a rotor whose operation is well-suited for use in micro-gravity conditions of space.
One more object of the invention is to provide rotor means for automating an enzyme-linked immunosorbent assay (ELISA) process and other, similar processes.